Gu Zuyu 顧祖禹 (1631-1692), courtesy name Gu Jingfan 顧景范, style Wanxi xiansheng 宛溪先生, was a geographer and historian of the early Qing period 清 (1644-1911). He came from Wuxi 無錫, Jiangsu, and developed an interest in geography already in his youth. With the end of the Ming dynasty 明 (1368-1644) he gave up aspiring an official career and only lived for his studies. As a result of his lecture of the Confucian Classics and historiographical writings he had become aware of the extreme importance of geographic desriptions and maps (yutu 輿圖) not only for the understanding of texts, but also for administrative purposes. For this field, treatises on river conservancy, border defense, "food and commodities" (shihuo 食貨), and the military system had a crucial value, but none of these fields was as importance as geography. He therefore investigated a huge number of texts to analyse all available information on the geography of China. The result of these researches are the two books Lidai zhouyu xingshi 歷代州域形勢 and Dushi fangyu jiyao 讀史方輿紀要. It was especially the latter book that provided details informations on the topology of the regions of China and connected them with military strategy. It was therefore called one of the "three great marvelous books in the empire" (hainei san da qishu 海內三大奇書), together with Mei Wending's 梅文鼎 Lisuan quanshu 歷算全書 and Li Qing's 李清 Nanbeishi hezhu 南北史合注. It was said that Gu Zuyu's book sufficed to instruct everyone about the physical geography of China without making it necessary to inspect individual regions by oneself.